Switchover mirror systems for periscopes are intended to permit viewing in two directions over viewing obstacles and preferably to the front and to the rear without it being necessary for the viewer to leave the viewing position when changing the sight direction.
Periscopic mirror systems with a switchover sight direction are disclosed, for example, in U.S. Pat. No. 4,123,151 incorporated herein by reference. With this known periscope, the incident beam is deflected via at least one mirror surface on the inner wall of the periscope shaft for one of the sight directions. The disadvantage of this known mirror system is that image cropping and sight field cropping must be accepted for oblique views or disturbing double images occur.